My game has only ui elements and its Heating up my phone

Hello unity answers family. I'm building a game with only ui elements. It's like text-based game . On my main menu scene, there are 4 images , 1 canvas , 1 panel . If i test this scene on my phone, my phone heats really fast. I don't get it. If i play a 2d text based game , and if this game heats up my phone (of course draining my battery) i do not wanna play that game. Do you know any solution for that ? My test phone is note 2. it has 7 batches , 7 draw meshes, without any scripts. And sorry for my poor English .